The first deciduous teeth that erupt in an infant are usually the primary incisors, and they appear between 6 and 16 months. 

The first tooth erupting is usually the medial (central) incisor (E, F, O, P), followed by the lateral incisor (D, G, N, Q).

The primary incisors are very similar to the secondary incisors, although they are smaller. These teeth have the shape of a shovel.

Deciduous incisors do not have developmental grooves.

Note: The mesiodistal length of the maxillary central incisors (E, F) is more significant than the incisocervical length.